Knot-Architectured Fabric Actuators Based on Shape Memory Fibers

Abstract

Due to recent progress on wearable robotics, developing high-performance fabric and textile actuators to be integrated with various soft electronic devices is urgently needed and remains a challenging issue. Here, a novel knot-architectured fabric actuator (KAFA), showing superior features such as self-locking crossing, mechanical robustness, facile fabrication at very low cost, high force generation, and large actuation strain, is reported. The actuation principle of KAFA is based on the shape recovery of constituent nitinol fibers that can restore the memorized curvature in the knotted architectures. Further, the KAFA can be conveniently operated by Joule heating, resulting in reliable actuation due to its seamlessly conductive circuit network. In addition, the KAFA shows exceptionally high force, up to 1373 times its own weight and around 30% actuation strain. The newly developed fabric actuators are applied to a wearable actuation device to lift weighty luggage and an adaptive controllable surface to grip spiky, irregular, fragile, and slippery objects. These applications demonstrate the wide potential of KAFAs for future wearable robotic products such as rehabilitative devices and powered exoskeletons.